Picture Tricks: Judging Picture Quality
The most important thing about testing for picture quality is to go with what you know. If at all possible, you should take a DVD or VHS that you are familiar with to the store and watch that on all prospects. Watching store-fed demo broadcasts is no way to judge picture quality. But if a movie you've seen a million times looks great to you, then you're on the right track.
Things to watch out for are adjustments to the brightness and other controls that affect the picture. Check out your prospect's display controls. (If you can't find them, ask your salesperson to show you where they are.) Set the brightness, color and contrast to their medium settings. It may not look as good now, but if you can shade the screen from the overhead lighting you will get a better idea of how the set will look in your darkened living room.
Once you get your set home, also be sure to check screen geometry -- lower-end sets may not have been properly calibrated at the factory, resulting in distorted images. If you notice image distortion -- pictures getting cut off, circles that look squeezed, squares that look like rectangles -- you may have to have the set professionally recalibrated. Note that some high-end TVs, such as rear-projection models, let you adjust the calibration yourself.
While on the subject of picture quality, there are a couple of features that TVs of varying price ranges include that will help picture quality in any environment.
In the next sections, we will discuss those features.
Comb Filters and 3:2 Pulldown
Comb filters are used to get the most out of the resolution of DVDs and other digital sources. They help to correct detail and color loss that occurs when your TV renders the signal onto the screen by layering several versions of the image on top of one another. The important thing to know about comb filters is that they come in three types:
|Two-line comb filter||Good|
|Three-line comb filter||Better|
|3D YC comb filter||Best|
Without a comb filter, you will only be seeing about 50 percent of a DVD's total picture quality. The thing to bear in mind is that your DVD player will only benefit from the comb filter if you hook it up to the TV using the composite video or RF connections. If your TV and DVD player support a higher quality connection type like component video or S-video, then a comb filter is unnecessary. It will still help, though, if you've used RF or composite jacks to hook up your digital cable box.
3:2 Pulldown Processing is rapidly becoming a standard in all TVs. It's a great feature that smoothes out pictures by correcting errors in frame rate.
Frame rate is the measurement used to calculate how many individual images are displayed in a second. Think of a flip book: You have several slightly different images, and as you flip through them quickly it appears as if there is a single, moving image. When you see a movie at the theater, the projector is operating like a flip book at a speed of 24 frames per second. The problem is that different formats operate at different frame rates. So when that same film you saw at the theater is transferred to a DVD, the frame rate jumps to roughly 29.8 per second. This can cause distortion in the image.
3:2 Pulldown Processing corrects the flaws that occur when film is transferred to another format. If you’re a film buff, then this is a feature to look for in your next set. For more information on 3:2 Pulldown Processing, including technical details, check out DVDFILE.com: What the Heck is 3:2 Pulldown?.
Vertical Compression and Color Temperature
Vertical compression mode is a feature on 4:3 televisions that helps to resolve some of the discrepancy between a DVD's resolution and the TV's resolution. It helps with formatting, too. This is something to look for if you're looking to get closer to a film-like look without springing for a 16:9 television.
Color temperature settings are seldom-talked-about features, but they can help the picture quality. Color on television is broken into red, green and blue (RGB). All the colors you see on your television are some combination of those three colors. Color temperature affects tone.
Tone has to do with the behavior of grays in the image, which are a mixture of the whites and blacks created by the television. These whites and blacks are also mixtures of RGB. Lighter shades rely on blue, while darker ones lean on red. What grey does to a TV image is add depth and subtleties. Imagine looking at a picture of a friend where all the subtle shadows in his face have been removed. This familiar face would lose depth and detail and look strange to you. Your brain uses these colors to establish relationships within an object you are looking at.
On a TV, color temperature affects the type of grey in the overall picture. In a TV store, they are going to crank this setting up as high as possible (closer to blue) to offset the overhead lighting in a store. In your home, you'll probably want to set it to its lowest (closer to red). Play with it in the store. You're looking for a neutral grey that adds depth and detail to the picture.